The invention relates to wafer carriers for handling silicon wafers used in the manufacture of semiconductors, and more particularly to a bottom loading wafer carrier box which provides a cavity which appopriately may have a still and particulate free environment for the wafer carrier and wafers.
Characteristic of the semiconductor manufacturing process is low yield. One reason for such low yields is particulate contamination of the wafers during their processing. Semiconductors have small wiring lines and spaces therebetween as minute as four microns. Foreign particulates not only may cause unwanted electrical bridges between such wiring lines, but also may cause electrical failures due to induced ionization or trapping centers in gate dialectrics or junctions. Therefore, keeping particulates and dust away from the silicon wafers during semiconductor manufacturing is vital because the circuitry etched thereon is extremely fine and a single particulate can ruin an entire semiconductor.
People, by shedding of skin flakes and hairs, are found to be a significant source of foreign particulates that form electrical bridges and are easily ionized thereby causing the defects. To control such particulate sources, the industry trend has been to build elaborate and expensive clean rooms with circulating air filter systems to obtain acceptable particulate-free levels of cleanliness.
Additionally, clean room garmets, including hoods and masks, are also commonly worn by clean room technicians to reduce particulate emissions into the clean rooms. Nonetheless, as many as six thousand particles per minute are still emitted into an adjacent cubic foot of clean room space by a fully suited technician or operator.